HEATER ON ALWAYS ?
Thread Starter
8th Gear
Joined: Jan 2003
Posts: 8
Likes: 0
From: Melbourne FL
HEATER ON ALWAYS ?
I've got a 69 BB convetible w/o A/C. As I understand the way GM has this thing plumbed, the coolant is always runinng through the heater core. Only difference between heater on or off is the openning of the air door. Since its now summer in Florida, and you can cook a prime rib in the passenger compartment of my Vette after about 10 minutes, would I lessen the heat if I were to put a shutoff valve in the coolant flow, or better yet, a bypass valve to redirect the flow around the heater core ?? Does anyone else have this problem ?? :confused:
Burning Brakes
Joined: Jun 2002
Posts: 792
Likes: 2
From: Norcross GA
Re: HEATER ON ALWAYS ? (klasik69)
Very common problem. I don't know about the earlier sharks but the later ones had vacuum controlled valves in the heater line.
Information at this web site. http://home.attbi.com/~jchadwick/ventilation.htm
Information at this web site. http://home.attbi.com/~jchadwick/ventilation.htm
Drifting
Joined: May 2002
Posts: 1,546
Likes: 5
From: Sacramento California
Re: HEATER ON ALWAYS ? (klasik69)
Yea, my 69 BB coupe has a vacuum control valve that is connected to the temp setting switch. When you select cool it closes the valve and no hot water circulates through the heater core.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: HEATER ON ALWAYS ? (klasik69)
Strangely enough...GM put a vacuum actuated shut off valve on non-A/C cars only. I guess they figured the A/C would compensate for the heater core always being on, and it was a comfort item...ideally GM designed the system to ALWAYS be in the BI-LEVEL setting so that the only control that needs to be adjusted is the temperature control. This worked fine for those that wanted a vette for comfort...if there ever was someone like that! :crazy:
It sounds like someone pulled yours, but most parts stores can get you one off the shelf as it was used for almost all non-A/C GM cars in the 70's...you will also need to splice in a vacuum line into the system so that the valve opens when the heater is turned on. I'm not sure how the non-A/C systems are set up, but I added one to my A/C system and it sure helps keep it cool in the cab.
It sounds like someone pulled yours, but most parts stores can get you one off the shelf as it was used for almost all non-A/C GM cars in the 70's...you will also need to splice in a vacuum line into the system so that the valve opens when the heater is turned on. I'm not sure how the non-A/C systems are set up, but I added one to my A/C system and it sure helps keep it cool in the cab.
Burning Brakes
Joined: Jun 2002
Posts: 792
Likes: 2
From: Norcross GA
Re: HEATER ON ALWAYS ? (Rockn-Roll)
Strangely enough...GM put a vacuum actuated shut off valve on non-A/C cars only.
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: HEATER ON ALWAYS ? (Bobchad)
My 69BB with A/C has a shut-off valve. I had a 71 w/ac that did not.. Catalogues list valves for some years and not others. I think they did the research for us. A far as I can tell they seem to be consistant and correct for what I have seen.
